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Wed, 14 Oct 2020 23:56:52 -0700 (PDT) X-Gm-Message-State: AOAM531HiBQQq1LbjkviWo/xdyvjVotCfTbgbruniEU0yXJySe5cadwW I/dXfuV76LwKGHgJQ6vPpDaoE47mhP/hl2p8aPs= X-Google-Smtp-Source: ABdhPJybOoY+mO/nEnFh3limcLTJvKxYdzD3nOrYwJKYP1LxI1gvd68IyrTKREOBe2vGTnarzIy1mGtBNPNgzjzm/u4= X-Received: by 2002:a05:6830:4028:: with SMTP id i8mr1614345ots.90.1602745011933; Wed, 14 Oct 2020 23:56:51 -0700 (PDT) MIME-Version: 1.0 References: <20201014191211.27029-1-nsaenzjulienne@suse.de> <20201014191211.27029-4-nsaenzjulienne@suse.de> In-Reply-To: From: Ard Biesheuvel Date: Thu, 15 Oct 2020 08:56:40 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address() To: Rob Herring X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201015_025654_817182_C6064820 X-CRM114-Status: GOOD ( 32.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Frank Rowand , Catalin Marinas , "linux-kernel@vger.kernel.org" , Jeremy Linton , Linux IOMMU , linux-arm-kernel , Robin Murphy , Christoph Hellwig , Nicolas Saenz Julienne , "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 15 Oct 2020 at 00:03, Rob Herring wrote: > > On Wed, Oct 14, 2020 at 2:12 PM Nicolas Saenz Julienne > wrote: > > > > Introduce of_dma_get_max_cpu_address(), which provides the highest CPU > > physical address addressable by all DMA masters in the system. It's > > specially useful for setting memory zones sizes at early boot time. > > > > Signed-off-by: Nicolas Saenz Julienne > > > > --- > > > > Changes since v2: > > - Use PHYS_ADDR_MAX > > - return phys_dma_t > > - Rename function > > - Correct subject > > - Add support to start parsing from an arbitrary device node in order > > for the function to work with unit tests > > > > drivers/of/address.c | 42 ++++++++++++++++++++++++++++++++++++++++++ > > include/linux/of.h | 7 +++++++ > > 2 files changed, 49 insertions(+) > > > > diff --git a/drivers/of/address.c b/drivers/of/address.c > > index eb9ab4f1e80b..b5a9695aaf82 100644 > > --- a/drivers/of/address.c > > +++ b/drivers/of/address.c > > @@ -1024,6 +1024,48 @@ int of_dma_get_range(struct device_node *np, const struct bus_dma_region **map) > > } > > #endif /* CONFIG_HAS_DMA */ > > > > +/** > > + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA > > + * @np: The node to start searching from or NULL to start from the root > > + * > > + * Gets the highest CPU physical address that is addressable by all DMA masters > > + * in the system (or subtree when np is non-NULL). If no DMA constrained device > > + * is found, it returns PHYS_ADDR_MAX. > > + */ > > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np) > > +{ > > + phys_addr_t max_cpu_addr = PHYS_ADDR_MAX; > > One issue with using phys_addr_t is it may be 32-bit even though the > DT is 64-bit addresses. LPAE capable system with LPAE disabled. Maybe > the truncation is fine here? Maybe not. > PHYS_ADDR_MAX is the max addressable CPU address on the system, and so it makes sense to use it for the return type, and for the preliminary return value: this is actually what /prevents/ truncation, because we will only overwrite max_cpu_addr if the new u64 value is lower. > > + struct of_range_parser parser; > > + phys_addr_t subtree_max_addr; > > + struct device_node *child; > > + phys_addr_t cpu_end = 0; > > + struct of_range range; > > + const __be32 *ranges; > > + int len; > > + > > + if (!np) > > + np = of_root; > > + > > + ranges = of_get_property(np, "dma-ranges", &len); > > I'm not really following why you changed the algorithm here. You're > skipping disabled nodes which is good. Was there some other reason? > > > + if (ranges && len) { > > + of_dma_range_parser_init(&parser, np); > > + for_each_of_range(&parser, &range) > > + if (range.cpu_addr + range.size > cpu_end) > > + cpu_end = range.cpu_addr + range.size; > > + > > + if (max_cpu_addr > cpu_end) > > + max_cpu_addr = cpu_end; > > + } > > + > > + for_each_available_child_of_node(np, child) { > > + subtree_max_addr = of_dma_get_max_cpu_address(child); > > + if (max_cpu_addr > subtree_max_addr) > > + max_cpu_addr = subtree_max_addr; > > + } > > + > > + return max_cpu_addr; > > +} > > + > > /** > > * of_dma_is_coherent - Check if device is coherent > > * @np: device node > > diff --git a/include/linux/of.h b/include/linux/of.h > > index 481ec0467285..db8db8f2c967 100644 > > --- a/include/linux/of.h > > +++ b/include/linux/of.h > > @@ -558,6 +558,8 @@ int of_map_id(struct device_node *np, u32 id, > > const char *map_name, const char *map_mask_name, > > struct device_node **target, u32 *id_out); > > > > +phys_addr_t of_dma_get_max_cpu_address(struct device_node *np); > > + > > #else /* CONFIG_OF */ > > > > static inline void of_core_init(void) > > @@ -995,6 +997,11 @@ static inline int of_map_id(struct device_node *np, u32 id, > > return -EINVAL; > > } > > > > +static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np) > > +{ > > + return PHYS_ADDR_MAX; > > +} > > + > > #define of_match_ptr(_ptr) NULL > > #define of_match_node(_matches, _node) NULL > > #endif /* CONFIG_OF */ > > -- > > 2.28.0 > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel